1. Field of the Invention
This invention relates to a display device for a camera, and to a method for controlling the display device. The invention relates in particular to a display device for displaying a stored image, for example, an image previously recorded by, and stored in, the camera.
The invention is particularly, but not exclusively, suited to document image cameras, i.e. cameras adapted for imaging documents, rather than general photography cameras. However, the invention is applicable to all forms of camera (for example whether they be document cameras, or general digital cameras, or video cameras) in which a display device is provided for displaying a stored image.
2. Description of Related Art
The displays on hand held digital cameras, and hand held video cameras, tend to be small. This is a result of the relatively high cost of current displays, and the desire for compactness for a portable camera.
Particularly when a stored image is a document image, in order to enable the document image to be reviewed in detail, a facility must be provided to enable zooming and scrolling of the document image in the small display. Additional manually operable controls are therefore required on the camera to enable the user to select an image to view, and then to zoom and scroll the display over the retrieved image.
The conventional approach is to provide additional control buttons on the camera, to provide the necessary control of the display. However, such an approach increases the complexity of the interface with the user. It is often difficult for a user to press the correct buttons, or simultaneous combination of buttons, to provide an optimal path to the region of the image to be viewed. The user may also have to take his or her eyes off the image to locate the desired control buttons, which makes the camera less convenient, and slower, to use. Moreover, control buttons do not enable the user to control variably the scroll speed or the zoom speed.
A touch sensitive display could be provided to allow the user to control the image by touching or dragging areas on the display screen. However, this normally requires both hands if the user is holding the camera. Touch screens can also be difficult to use particularly on small displays. If the user's finger is large relative to the display, then the finger cannot be moved very far and the finger occludes the user's view of the image. Additionally, a small display will usually be near the user's eye, which makes the display difficult to access with the finger. Such closeness also means that the user's finger and the display itself will not be simultaneously in focus.
U.S. Pat. No. 5,844,824 describe a hands-free portable computer which uses eye-tracking for shifting the effective field of view in the display. However, such displays are more complex and expensive, and presently less reliable to use.
Reference may be made to head-mounted displays (e.g. U.S. Pat. No. 6,011,526) and to tip-tilt Personal Data Assistants (PDA's).